1 files changed, 200 insertions, 0 deletions
diff --git a/llvm/lib/Support/Windows/Memory.inc b/llvm/lib/Support/Windows/Memory.inc
new file mode 100644
index 000000000000..a67f9c7d0f35
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+++ b/llvm/lib/Support/Windows/Memory.inc
@@ -0,0 +1,200 @@
+//===- Win32/Memory.cpp - Win32 Memory Implementation -----------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides the Win32 specific implementation of various Memory
+// management utilities
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/Process.h"
+#include "llvm/Support/WindowsError.h"
+
+// The Windows.h header must be the last one included.
+#include "WindowsSupport.h"
+
+namespace {
+
+DWORD getWindowsProtectionFlags(unsigned Flags) {
+  switch (Flags & llvm::sys::Memory::MF_RWE_MASK) {
+  // Contrary to what you might expect, the Windows page protection flags
+  // are not a bitwise combination of RWX values
+  case llvm::sys::Memory::MF_READ:
+    return PAGE_READONLY;
+  case llvm::sys::Memory::MF_WRITE:
+    // Note: PAGE_WRITE is not supported by VirtualProtect
+    return PAGE_READWRITE;
+  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_WRITE:
+    return PAGE_READWRITE;
+  case llvm::sys::Memory::MF_READ|llvm::sys::Memory::MF_EXEC:
+    return PAGE_EXECUTE_READ;
+  case llvm::sys::Memory::MF_READ |
+         llvm::sys::Memory::MF_WRITE |
+         llvm::sys::Memory::MF_EXEC:
+    return PAGE_EXECUTE_READWRITE;
+  case llvm::sys::Memory::MF_EXEC:
+    return PAGE_EXECUTE;
+  default:
+    llvm_unreachable("Illegal memory protection flag specified!");
+  }
+  // Provide a default return value as required by some compilers.
+  return PAGE_NOACCESS;
+}
+
+// While we'd be happy to allocate single pages, the Windows allocation
+// granularity may be larger than a single page (in practice, it is 64K)
+// so mapping less than that will create an unreachable fragment of memory.
+size_t getAllocationGranularity() {
+  SYSTEM_INFO  Info;
+  ::GetSystemInfo(&Info);
+  if (Info.dwPageSize > Info.dwAllocationGranularity)
+    return Info.dwPageSize;
+  else
+    return Info.dwAllocationGranularity;
+}
+
+// Large/huge memory pages need explicit process permissions in order to be
+// used. See https://blogs.msdn.microsoft.com/oldnewthing/20110128-00/?p=11643
+// Also large pages need to be manually enabled on your OS. If all this is
+// sucessfull, we return the minimal large memory page size.
+static size_t enableProcessLargePages() {
+  HANDLE Token = 0;
+  size_t LargePageMin = GetLargePageMinimum();
+  if (LargePageMin)
+    OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY,
+                     &Token);
+  if (!Token)
+    return 0;
+  LUID Luid;
+  if (!LookupPrivilegeValue(0, SE_LOCK_MEMORY_NAME, &Luid)) {
+    CloseHandle(Token);
+    return 0;
+  }
+  TOKEN_PRIVILEGES TP{};
+  TP.PrivilegeCount = 1;
+  TP.Privileges[0].Luid = Luid;
+  TP.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
+  if (!AdjustTokenPrivileges(Token, FALSE, &TP, 0, 0, 0)) {
+    CloseHandle(Token);
+    return 0;
+  }
+  DWORD E = GetLastError();
+  CloseHandle(Token);
+  if (E == ERROR_SUCCESS)
+    return LargePageMin;
+  return 0;
+}
+
+} // namespace
+
+namespace llvm {
+namespace sys {
+
+//===----------------------------------------------------------------------===//
+//=== WARNING: Implementation here must contain only Win32 specific code
+//===          and must not be UNIX code
+//===----------------------------------------------------------------------===//
+
+MemoryBlock Memory::allocateMappedMemory(size_t NumBytes,
+                                         const MemoryBlock *const NearBlock,
+                                         unsigned Flags,
+                                         std::error_code &EC) {
+  EC = std::error_code();
+  if (NumBytes == 0)
+    return MemoryBlock();
+
+  static size_t DefaultGranularity = getAllocationGranularity();
+  static size_t LargePageGranularity = enableProcessLargePages();
+
+  DWORD AllocType = MEM_RESERVE | MEM_COMMIT;
+  bool HugePages = false;
+  size_t Granularity = DefaultGranularity;
+
+  if ((Flags & MF_HUGE_HINT) && LargePageGranularity > 0) {
+    AllocType |= MEM_LARGE_PAGES;
+    HugePages = true;
+    Granularity = LargePageGranularity;
+  }
+
+  size_t NumBlocks = (NumBytes + Granularity - 1) / Granularity;
+
+  uintptr_t Start = NearBlock ? reinterpret_cast<uintptr_t>(NearBlock->base()) +
+                                NearBlock->allocatedSize()
+                           : 0;
+
+  // If the requested address is not aligned to the allocation granularity,
+  // round up to get beyond NearBlock. VirtualAlloc would have rounded down.
+  if (Start && Start % Granularity != 0)
+    Start += Granularity - Start % Granularity;
+
+  DWORD Protect = getWindowsProtectionFlags(Flags);
+
+  size_t AllocSize = NumBlocks * Granularity;
+  void *PA = ::VirtualAlloc(reinterpret_cast<void *>(Start),
+                            AllocSize, AllocType, Protect);
+  if (PA == NULL) {
+    if (NearBlock || HugePages) {
+      // Try again without the NearBlock hint and without large memory pages
+      return allocateMappedMemory(NumBytes, NULL, Flags & ~MF_HUGE_HINT, EC);
+    }
+    EC = mapWindowsError(::GetLastError());
+    return MemoryBlock();
+  }
+
+  MemoryBlock Result;
+  Result.Address = PA;
+  Result.AllocatedSize = AllocSize;
+  Result.Flags = (Flags & ~MF_HUGE_HINT) | (HugePages ? MF_HUGE_HINT : 0);
+
+  if (Flags & MF_EXEC)
+    Memory::InvalidateInstructionCache(Result.Address, AllocSize);
+
+  return Result;
+}
+
+  std::error_code Memory::releaseMappedMemory(MemoryBlock &M) {
+  if (M.Address == 0 || M.AllocatedSize == 0)
+    return std::error_code();
+
+  if (!VirtualFree(M.Address, 0, MEM_RELEASE))
+    return mapWindowsError(::GetLastError());
+
+  M.Address = 0;
+  M.AllocatedSize = 0;
+
+  return std::error_code();
+}
+
+  std::error_code Memory::protectMappedMemory(const MemoryBlock &M,
+                                       unsigned Flags) {
+  if (M.Address == 0 || M.AllocatedSize == 0)
+    return std::error_code();
+
+  DWORD Protect = getWindowsProtectionFlags(Flags);
+
+  DWORD OldFlags;
+  if (!VirtualProtect(M.Address, M.AllocatedSize, Protect, &OldFlags))
+    return mapWindowsError(::GetLastError());
+
+  if (Flags & MF_EXEC)
+    Memory::InvalidateInstructionCache(M.Address, M.AllocatedSize);
+
+  return std::error_code();
+}
+
+/// InvalidateInstructionCache - Before the JIT can run a block of code
+/// that has been emitted it must invalidate the instruction cache on some
+/// platforms.
+void Memory::InvalidateInstructionCache(
+    const void *Addr, size_t Len) {
+  FlushInstructionCache(GetCurrentProcess(), Addr, Len);
+}
+
+} // namespace sys
+} // namespace llvm